A new national study showing that 70 percent of women with the most common type of breast cancer don’t benefit from chemotherapy is “a big deal,” said at least one local expert.

“That’s a lot more patients who are not going to need chemotherapy,” said Dr. Denise Barajas, medical director for the Hewitt Center for Breast Health at Griffin Hospital in Derby. “This is great, because chemotherapy is very toxic, and if people aren’t benefiting from it, you don’t have to prescribe it.”

The Trial Assigning Individualized Options for Treatment, also known as the TAILORx trial supported by the National Cancer Institute, opened in 2006 and was designed to determine whether hormone therapy alone is inferior to hormone therapy plus chemotherapy when it comes to treating certain kinds of breast cancer.

After skin cancer, breast cancer is the most common cancer in American women, according to the American Cancer Society. There is a one-in-eight chance a woman will develop breast cancer in her lifetime. Though chemotherapy is sometimes used to treat breast cancer, it can carry serious side effects, including hair loss, fertility issues, infection, fatigue and memory loss.

In some cases, chemotherapy itself can lead to serious illness, said Erin Fusco, visiting assistant professor of nursing at Quinnipiac University.

“The side effects are so difficult for some people to deal with,” she said. “Some of these medicines can be very harsh.”

More than 10,000 women with early stage, HR-positive, HER2-negative, axillary lymph node-negative breast cancer were enrolled in the TAILORx trial at 1,182 sites in the U.S., Australia, Canada, Ireland, New Zealand and Peru.

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Fast facts on TAILORx

Here are a few facts on the TAILORx trial, which studied whether women with the most common kind of breast cancer got more benefits from chemotherapy combined with hormone therapy than from hormone therapy alone.

Women with an intermediate risk of breast cancer recurrence were randomly assigned to be treated just with hormone therapy or with a combination of chemo and hormone therapy.

Five years after treatment, the rate of disease-free survival was 92.8 percent for those who had hormone therapy alone and 93.1 percent for those who also had chemo.

Nine years after treatment, the rate was 83.3 percent for those with hormone therapy alone and 84.3 percent for those with both therapies.

The findings suggest that chemotherapy may be avoided in about 70 percent of women with the type of cancer studied.

Source: The National Institutes of Health’s National Cancer Institute

The tumors of participants were analyzed using a 21-gene expression test, which determined the risk for breast cancer recurrence. They were assigned a score between 0 and 100 based on how likely their cancer was to recur.

Barajas said earlier research has shown that women with a low risk score (between 0 and 10) could receive hormone therapy only, and that those with a risk score of 26 or higher should be treated with a combination of hormone therapy and chemotherapy.

But, as for those with scores between 11 and 25 “we didn’t know what to do,” Barajas said. “Some patients in that group would choose to have chemotherapy if they thought it would have some benefit, and some chose not to.”

Barajas said she and other doctors hoped the TAILORx trial would provide more direction on what to do with these so-called “intermediate” patients who were neither high risk or low risk.

Similar rates

For the study, patients in the intermediate range were randomly assigned to receive either hormone therapy alone, or hormone therapy combined with chemotherapy. What researchers found was that the proportion of women who had not died or had a recurrence or new cancer was similar in both groups.

According to the researchers, five years after treatment, the rate of disease-free survival was 92.8 percent for those who had hormone therapy alone and 93.1 percent for those who also had chemo. The overall five-year survival rate was 98 percent for those who received hormone therapy alone and 98.1 percent for those who received both therapies.

Ultimately, the study concluded that most women with an intermediate recurrence score could avoid chemotherapy and do only hormone therapy. However, researchers did find that a small group of these women — those 50 and younger with a risk recurrence score of 16 to 25 — might still benefit from chemotherapy.

Fusco said there will need to be some validation studies done before the findings of the study become standard practice in treating cancer. But, she said, the project certainly feels like a game changer for women with certain kinds of breast cancer.

“It’s a lot to undergo chemotherapy,” Fusco said. “So if you don't have to undergo it, that’s huge.”